Automatic toaster



April 9,4 1940- H. M. BIEBEL 2,196,380

' :n.vronm'rc ToAsTER A A Filed Feb. 2o, 1939 2 sheets-sheet x Inven't'or; I Herman M. Btebel.

April 9, 194g.

` Fig-4 Filed Feb. 20. 1939 v H. M. BIEBEL- AUTOMATIC TOASTER 2 Sheets-Sheet 2 'tiert-nw' Patented Apr. 9,

PATENT or-'Fica AUTOMATIC TOASTEB Y Herman M. Biebel, Elgin, Ill., assigner to McGraw Electric Company,

poration o! Delaware Elgin. 111.', a cor- 'appucamn February zo, 1939, serial No. 257,301

My invention relates to cooking devices and particularly to automatic electric toasters.

Among the objects of my invention are the following:

To provide a relatively simple thermal timing device for an automatic electric toaster;

To provide an all electric thermal timing device for an automatic electric toaster that shall be highly sensitive in its operation;

ITo provide a thermal timing device for an automatic electric toaster that shall embody a,

thermal element responsive to toaster chamber temperature to insure substantially uniform toasting of successive slices of bread irrespective of changes in the temperature of the toaster;

And finally to provide a thermal timing device operating on the heat-up cool-off principle during any one toasting operation. In the drawings, A

Figure 1 is a vertical sectional view on the line I-l of Fig. 2 showing a part of a baiiie plate broken away to disclose certain inner parts, Fig. 2 is a view in frontl elevation showing the casing in section and taken on the line 2-2 of Fig. 1, l

Fig.- 3 is a fragmentary vertical sectional view taken on the line 3 3 of Fig. 7,-

Fig. 4 is a fragmentary horizontal sectional view taken on the line 4-4 of Fig. 2, Fig. 5 is a fragmentary vertical sectional view taken on the line 5 5 of Fig. 4 showing pare ticularly the .detent and the electric releasing mechanism,

Fig. 6 is a fragmentary view showing a part 85 of the device shown in Fig. 1 but with the parts positioned in operating or toasting positions,

Fig. 'I isA an enlarged vertical sectional viewtaken on the line '1 -'I of Fig. 1v showing a main'y bimetal bar, its associated contact members and n an auxiliary or compensating bimetal bar, and Fig. V8 is a schematic wiring diagram used in my improved toaster control means.

An automatic electric toaster assembly i l *includes a frame I3 which may be made of moulded composition material having a crumb tray I5 secured thereto and having also a base plate Il of thin sheet metal secured thereto in any suitable or desired manner at the top surface of member i3. A casing i9 having front, rear and side walls. is mounted on member i3 and may be -held thereonin any suitable or desired manner now well known in the art. A cover member 2l isprovided at the upper end of casing I9, which is provided Vwith one or more slots 23 therein through. which slices of bread may s claims. (ci. 21e-19) be inserted into and removed from the toasting chamber.

A plurality of `planar heating elements include respectively one or more vertically extending thin sheets of electric-insulating material 25 3 on which is wound a heating resistor 21 all in a manner now well known in the art. I prefer to provide a pair of spaced electric heating elements of the kind just above described for each slice of bread adapted to be toasted in the 1@ toaster. While I have shown my toaster as being provided with four such electric heating elements, my invention is not 4limited to such number and I may use either a greater or a lesser number of such pairs-of heating elements. x5

The outermost heating elements and particularly the sheets 0i electric insulating material 25 thereof cooperate with a rear intermediate wall 29 and a iront intermediate'wall 3|, both preferably of thin sheet metal, to inclose a toasting chamber, the bottom of which is constituted by plate i1 yand the top of which may be constituted by cover 2l. The bottom plate i'i may be provided with openings 33 therein registering with the space between pairs of heating ele- 23 ments and with the openings 23 in the cover to permit of proper ventilation of the toasting chamber, when the toaster is in operation. In

order toreduce the loss of heat outwardly from the outermost heating elements I may provide 3g baille plates at each side oi' the toaster. A pair oftop' frame plates 3l are provided, one

for each slice of bread, which plates may be used to properly locate the upper edges of the heating elements and which may also be used to support guard and guide vWires 39 in a manner well known in the art.

Terminal members 4I (see Fig. 1) maybe insulatedly mounted on the rear intermediate wall 29 and a twin conductor cord 43 may be provided to permit 'of energizing the heating elements of the toaster all in a manner well known in the art. i

Means for controlling the energi'zation of the l main, heating 'resistor elements 21 may include termediate wall 29. A biasing spring 59 has one end thereof connected with the lower end of arm 55 while its other end is adapted to engage with any one of a plurality of teeth now shown provided near the forward edge of base plate I1, all

` in a manner known in the art.

Meansfor initiating a toasting operation in-V cludes a carriage 5| having an upper pair of rollers 33 and a lower pair of rollers 55, engaging on opposite sides of a central vertical standard 61, the lower end of which ilts into and is held by the base plate I1 while the upper end thereof fits into a cross bar i9, the ends of which may be supported -by the pair of upper frame 'plates 31 all in a manner well known in the art. A slider 1I is adapted to move vertically and reciprocally on a left-hand'standard 13 and a second slider 15 is adapted to move on a right-hand vertical standard 11. the lower ends of which standards may fit into and be held by the base plate I1 and the upper ends of which may t into and be held by forwardly extending portions of top frame plates 31 and of the cross bar 69, all of these details being well known in the art. Bread carriers 19, in this case two in number, are severally adapted to move vertically in the space between each pair of cooperating heating elements 25 and have rear end portions extending through and moving in vertical slots 8| in rear intermediate wall 29 while forwardly extending portions 83 move in slots 85 in front intermediate wall 3|. The portions 83 are secured to therespective sliders 'II and 15 which have rearwardly extending portions for that purpose. A cross rod 81 is secured to the slider 1| and 15 and may have a roller 89 thereon which is adapted to move in a slot 9| in the forward end of arm 53.

A plate 93 having an angular slot 95 therein is secured to and against the outer face of slider 1|, and a pin 91 projecting laterally from the upper end ofswitch-arm 41 is adapted to move in the slot 95, the 'design construction and adjustment of these parts being such that when the operator presses on a knob 99 positioned on the outside of the casing and secured on a member IUI mountedon carriage 9|, the carriers 19 will be moved downwardly from the non-toasting position shown in Fig. 1 to the toasting position shown in Fig. 6 of the drawings, the coil spring 59 will be placed under tension. and switch-arm 41 will be caused to turn in a clockwise direction to close the circuit through the main heaters 21.

I have described in some detail the structural elements of a toaster assembly with which the parts now to be described and more particularly y constituting my invention may be associated.

It is obvious, however, since all of the hereinbefore described 'details are old. that I am not limited to only suchdetails, as these have been shown and described for illustrative purposes only.

It may be here pointed out that I provide a detent member |93 for the bread carriers. shown particularly in'Figs. 1 and 5 or the drawings, which detent is pivotally mounted at |05 in a bracket |91 and is biased by a spring |09 to a position where it may engage with a lug III secured to or part of right-hand slider 15. When aieaseo the knob 99 has been moved downwardly by an operator to initiate a toasting operation, member I I i will be engaged below the lower end of detent |03, as seen more particularly in Fig. 6 of the drawings, so that for a limited time the switch remains closed and the bread carriers are in their toasting position with any slice or slices of bread supported thereby subject to heat from the heating resistors 21 to cause toasting. Certain of the movable parts hereinbefore described constitute the means for initiating a toasting operation and means for terminating a toasting operation will now be described, these means constituting more particularly my present invention.

A main bimetal element I I3 which may for convenience be called the main thermobar, is insulatedly supported in a small casing ||5 which casing is secured to the under side of base plate I1 in any suitable or desired manner, which may include a plurality of short machine screws II1 as is showny more particularly ln Fig. 7 of the drawings. While a part of the casing is located below the base plate I1, I may have the upper part thereof extend above the base plate I1 an opening |I9 (Fig. 3) being provided in the base plate to permit of such location. The bottom wall or a side of the casing I I5 may be provided with one or more openings I2| (Fig. 7) and the upper wall of the casing ||5 may be provided with at least one opening |23 therein in order to permit of a through draft of cooling air to ilow through the casing |I5 when the toaster is in operation. It may be here noted that an opening |25 (see Fig. 5) may be provided in front intermediate wall 3| to permit of such draft of cooling air flowing through the casing I I5 and out through one of the openings 23.

The main thermobar I I3 may have an auxiliary heating resistor |26 insulatedly mounted thereon or if desired, I may provide any other suitable supporting means for this heating resistor in a manner well known in the art. A fixed contact member |21 is insulatedly supported in the casing ||5 as from the bottom wall thereof.

A compensating or auxiliary thermobar |29 is supported in close heat-receiving relation to and with the front intermediate wall 3| as by a metal bracket I3I (see Fig. 3). A contact member |33 is insulatedly mounted on and supported by the free or movable end of thermobar |29. It may be here pointed out that it is desired that auxliary thermobar |29 be subject to heat from the toasting chamber transmitted through the front intermediate wall 3| thereof and through the bracket |3| and I may make the engaging surface of the` bracket |3| and ofthe front intermediate wall 3| relatively large in order to have a relatively large amount of heat transmitted from the having magnetic core |45 therein and having an to ilxed contact |53. contact spring |51, through A plurality of xed contact members and |53 are insulatedly mounted on' a bracket |55 which bracket may be constituted by a metal strip Aof flat channel shape secured to the front intermediate wall 3| (see Fig. 5). A pair of spring contact members |51 and |59 are also insulatedly Y supported on the bracket |55 as shown particuother supply circuit conductor |83. By reference to the other supply circuit conductor |83.

larly in Fig. 5 of the drawings, spring' contact |51 being adapted to engage with contact member |53 but being normally biased away .therefrom. Spring contact |59 is adapted to be moved into engagement with contact |5| by armature |41 when coil |43 is energized but is normally. biased into engagement with a fixed contactv member 6| insulatedly mounted on bracket |55. An electromagnetic detent release means is also supported from bracket |55 and includes a solenoid |63 having an armature core |65 vertically movable therein, which core has at its lower end a pivotally mounted release member |61 which member is adapted to move past a rearwardly projecting lug |69 of detent |83 when the armature core |65 moves downwardly but which member is adapted to engage and cause clockwise turning releasing movement of detent |03 when core member |55 moves upwardly on energize.- tion of coil |63. A lstop 1| maybe provided to limit the downward movement of core |65.

Referring now particularly to Fig. 8 of the drawings, I have there shown a wiring diagram 0f the toaster, two resistors 21 only being shown although any desired number of such resistors are to lbe considered as being indicated thereby. On downward movement of knob 99 to initiate a toasting operation with attendant downward movement of the carriage, sliders and bread carriers and engagement of contact members 41 and 45 not only will the heating resistors 21 in the toaster beenergized but the auxiliary heating coil |26 will also be energized. the circuit therefor being as follows: From supply circuit conductor |13 through switch contacts 45 and 41, conductors |15 and |11 through spring contact |59 to contact |6|, conductor |19, auxiliary heating resistor |26 and through a conductor |8| to the to Fig. 8 of the drawings it will be noted that main. thermobar ||3 and particularly a contact member thereon may initially be in engagement with xed contact member |21 but any circuit including these parts will be incomplete since it is open at contact member |51. Y

Energization of the auxiliary heater |26 causes an increase in temperature of the main thermobar H3 which is so designed and constructed that its free end will move upwardly in a counterclockwise direction when heated. At a given position of the auxiliary or compensating thermobar |29 the'main' thermobar ||3 will engage with contact member |33 on thermobar |29 whereby the following circuit will be established; from supply circuit conductor |13 through contacts 45 and' 51, conductor |81, coil |43 of the relay, conductor |85. contact |33, through thermobar H3, The energized coil |43 actuates the pivotally mounted armature |41 causing movement of the spring contacts |51 and |59 in a clockwise direction whereby the energizingcircuit through resistor coil 43 as follows:

|28 is interrupted by disengagement of contact member |59 from contact member lill.` At the same time a holding circuit is established for From supply circuit conductor |13 through contacts 45 and 41. through nductor |91, through coil |83., conductor iol conductor |89 and to the .other suppl! circuit conductor |83. 'Ihis insures that the coil |48 ot-the relay will remain energized even though the main Vthermobar |13 on cooling moves in a clockwise direction to disengage contact member |33.

At the same time a detent releasing circuit is .prepared as' follows: From supply circuit conductor |13 through contacts 45 and 41, conductors |15 and |11, spring contact |59, contact |5|,/ conductor |93, coil |63 of the-detent releasing means and through a conductor |95 to contact member |21.

When the main thermobar H3 has been cooled to a predetermined lowerftemperature it will have moved in a clockwisedirection and the contact member thereon will engage xed contact` member |21 whereby the initially incomplete energizing circuit through coil |63 of the electromagnetic detent release means will be closed through main thermobar H73 and to supply circuit conductor |83. This causes upward movement of core |65 with attendant turning movement of detent |03 in aclockwise direction because of the engagement of member |61 with lug |59, whereby termination of a toasting opt eration is eiected, the spring 59 causing upward movement of the carrier 19 and simultaneous deenergization of the main or toasting resistors 21, by disengagement of the contacts and 41.

I may here point kout that the main thermobar ||3 is preferably so positioned with relation to the toasting chamber andthe main heating resistors therein, as lto be only slightly aiected thereby. The cooling draft of air entering the casingl H5 at opening I 2| and leaving the casing at the upper opening |23 flowing upwardly in the small chamber in front of front intermediate Wall 3| and 'then through opening |25, will assist materially in quick cooling of the main thermobar H3 when such cooling is in order after deenergization of the auxiliary heating element operatively associated therewith.

described as to the deenergization of the auX- iliary heater |26 and energization o1' coil |43 of the relay. It is obvious ,that the distance between contact |33 and thecontact on arm i i3 decreases with increase in toaster temperature to which the bimetal bar |29 is subjected. This will result in decreasing the duration of a toasting operation with increased temperature of the toaster assembly. l

It is also obvious that this length of time of theA heat-up portion of the cycle of the main thermobar 3 can be varied by manual adjustment of the cam |35 to vary the initial position of thermobar |29 relatively to thermobar A| E3.

The device embodying my invention thus provides a relativelyl simple an'd compact thermal timing means operating on the heat-up, cool-on principle to control the duration of a toasting operation. It is obvious that the use of electrothermobar to be made relatively light and therefore to have a relatively small thermal mass and thermal lag which of course makes for increased sensitivity to temperature changes. It is further obvious that since relatively slight pressures only are necessary for the engaging contact members, the main and the auxiliary thermobar need not be subjected to relatively large mechanical stresses thereby insuring that any adjustment made at the factory will remain unchanged over long periods of time under ordinary operating conditions.

While I have illustrated and described a particular embodiment of my invention, I do not desire to be limited strictly thereto since modifications within the scope v of -the appended claims can be made.

I claim as my invention:

1. In an automatic electric toaster, the combination with a main electric heater energizable only during a toasting operation, a control switch for said main heater biased to open position, a detent for holding said switch closed, an electromagnetic release means for said detent and a thermal timing means comprising an auxiliary heater and a single thermobar adapted to be heated up by said auxiliary heater and then cooled off during a giventoasting operation, of an electromagnetic relay including a solenoid and contacts actuable thereby and electric connections between said relay, its contacts and said thermobar whereby on closing said control switch to initiate' a toasting operation said auxiliary heater is energized through normally closed relay contacts, said thermobar thereupon being heated and becoming effective, when heated to a predetermined temperature, to energize said lsolenoid to open the circuit through said auxiliary heater, to cause said solenoid to close a holding circuit for itself and to prepare a circuit through said electromagnetic release means, cooling of said thermobar to a predetermined lower temperature causing closing of a circuit through said electromagnetic release means and termination of a toasting operation and opening of all circuits in the toaster.

2. In an automatic electric toaster, the combination with a casing, a main electric heater therein energizable only during a toasting operation and means for initiating a toasting operation, of means for terminating a toasting operation comprising a main thermobar out of close heat receiving relation to said main heater, an auxiliary electric heater for heating said main thermobar, an auxiliary thermobar in close heat receiving relation to said main heater, and carrying a contact, an electromagnetic relay including a coil and a plurality of contacts controlled thereby, electric connections between said relay coil, contacts and said main thermobar, initiation of a toasting operation causing energization of said main and auxiliary heater, said main thermobar being effective when it has been heated to a predetermined temperature to effect energization of said relay coil and of a holding circuit therefor and deenergization of said auxiliary heater, said main thermobar thereupon cooling and effecting termination of a toasting operation when it has cooled to a predetermined lower temperature, said auxiliary thermobar Substantially closely following toaster temperature and cooperating with the main bimetal bar to cause uniform toasting of successive slices of bread irrespective of changes in operating conditions of the toaster.

V3. In an automatic electric toaster, the combination with a casing,Y a main electric heater therein energizable only during a toasting operation and means for initiating a toasting operation, of means for terminating a toasting operation comprising a main thermobar, an auxiliary electric heater for heating said main thermobar, a ventilated casing in which said main thermobar and said auxiliary heater mounted to substantially heat insulate them from the main electric heater, an auxiliary thermobar mounted in close heat receiving relation to said main electric heater and carrying a contact, an electromagnetic relay having contacts thereon, electric connections between said main thermobar, relay coil and said contacts, actuation of said initiating means causing current iiow through said main and said auxiliary heaters, said main thermobar being` effective when heated to a predetermined temperature to engage the contact on said auxiliary thermobar and energize said relay coil, said coil thereupon eiecting movement of certain of its contacts to deenergize said auxiliary heater said main thermobar then cooling and terminating a toasting operation when its temperature has reached a. predetermined low value.

4. A device as set forth in claim 3 and including a manually actuable mechanical means for varying the initial position of said auxiliary thermobar to vary the duration of a toasting operation.

5. In an automatic electric toaster, the combination with a main electric heater, a control switch therefor biased to open position, a detent for holding said switch in closed position and an electromagnetic release means for said detent, of a thermal timing means for determining the duration of a toasting operation in accordance with the temperature of the toaster, said timing means including an auxiliary electric heater, a main thermobar to be heated by said auxiliary heater, a ventilated casing enclosing said auxiliary heater and said thermobar and substantially shielding them from the heat of the toaster, an auxiliary thermobar subject to the heat of the toaster, a plurality of contacts electromagnetically controlled by said main thermobar, closing of said control switch causing energization of said main and said auxiliary heater, said main thermobar being effective when it has been heated to a predetermined high temperature to effect deenergization of the auxiliary heater and cooling of the main thermobar, said main thermobar becoming eiective to energize the electromagnetic detent release when the temperature of the main thermobar has reached a predetermined low Value, the auxiliary thermobar cooperating with the main thermobar to energize the detent release sooner when a toaster is operated at a high temperature than would occur when a toaster is operated at a lower temperature.

HERMAN MBIEBEL. 

